Nov. 5, 2002 -- Long-term hormone replacement therapy has been all but abandoned for the prevention of disease in the months since a large government study linked its use to an increased risk of heart attack, blood clots, and breast cancer. But the same study found HRT helps protect against bone loss, and new research suggests it may protect against Alzheimer's disease in women who take it around the time of menopause.
The study found that elderly women with a history of hormone use were less likely to develop Alzheimer's than those who had never taken HRT. But current users who had taken HRT for less than 10 years developed the disease at an increased rate compared with women who took HRT for more than 10 years.
"This study suggests that use of hormone therapy within 10 years of onset of Alzheimer's disease is not protective," researcher John C.S. Breitner, MD, tells WebMD. "Several other studies have shown that hormone therapy is of no value in women who have already developed Alzheimer's. Our data suggest that even for women with very mild cognitive impairment it may be too late."
In their study, published in the Nov. 6 Journal of the American Medical Association, Breitner and colleagues followed about 3,200 elderly residents of a county in Utah who were taking part in an ongoing observational study. None of the participants had Alzheimer's at enrollment in 1995, but 2.6% of the men and 4.7% of the women were diagnosed with the disease three years later.
Women who used HRT were found to have a 41% reduction in risk of developing Alzheimers disease, compared with women who had never taken hormone therapy. Women who took HRT for more than 10 years had the same risk for Alzheimer's as men, and longer use was associated with larger risk reductions. So women who had taken HRT for more than 10 years had decreased their risk of developing the disease.
In an effort to determine whether an overall healthier lifestyle was responsible for the decreased risk among HRT users, the researchers also examined the use of multivitamin and calcium supplements. Supplement use was not found to be protective against Alzheimer's. But Breitner says the findings cannot exclude the possibility that HRT users differ from nonusers in other important attributes related to health in general and Alzheimer's in particular.
While the findings indicate that women who take HRT around the time of menopause may derive cognitive benefits years later, Breitner says the study is far from definitive. Alzheimer's researcher Susan M. Resnick, PhD, of the National Institute on Aging, tells WebMD that data on dementia risk from the Women's Health Initiative (WHI) trial due to be published within the year should help clarify the issue. The dual-hormone therapy arm of the WHI was halted earlier this year when researchers concluded that the HRT drug Prempro is associated with an increased risk of heart attack, stroke, blood clots and breast cancer. But they have yet to publish their findings on Alzheimer's risk.
Resnick says it is too soon to recommend that women take HRT solely for the prevention of Alzheimer's disease. In an editorial accompanying the study she writes that the results "offer both hope for a possible neuroprotective effect of hormone therapy and frustration that it could be difficult to determine the optimal timing of treatment."
"Unfortunately, we are going to have to wait for the research to evolve over the next few years," she tells WebMD. "Only very preliminary information has been put out there so far with regard to HRT and Alzheimer's. And ultimately, I think the decision to take HRT or not take HRT will be based on individual risk factors."